| Serious social and economic hazards could be happened when destabilization damage occurs in tailings dams.The consideration of soil layer interface effects in the stability analysis of tailings dams is an important factor that has received limited attention in related research.Taking the Qinhuangdao Mingtangzi tailings dam project as the research object,the soil interface effect was introduced with the help of indoor shear experiment and numerical simulations to carry out the stability analysis of the dam.The microscopic analysis of three kinds of tailing soil materials was carried out by scanning microscope;the mechanical properties of tailing soil samples under different water content conditions and percolation state were analyzed with the help of direct shear experiment.The experiment results showed that the particles of tailings medium sand were the largest and its surface was the roughest,and crystals and colloidal substances of sodium,magnesium or aluminum are attached on the surface of tailings soil material;with the increase of water content,a peak was appeared of the cohesive force,and the angle of internal friction continued to decrease.;the cohesive force and internal friction angle of the tailing soil under different heights of water showed a stepwise decrease phenomenon.The three different combinations were set up for experimental analysis when analyzing the interface effect of tailings soil layers.The experiment results showed that the mechanical properties of the interface are between the two different soil layers;With the increase of water height,the mechanical properties of soil interface showed a downward trend.Based on Bishop method,sectional method and strength reduction method,the stability calculation model of dam under different water levels was simulated using the Li Zheng rock-soil and FLAC3 D.The fluid-solid coupling calculation of the dam was carried out,and the mechanical property parameters of the tailings layer interface were introduced in FLAC3 D to calculate the safety factor of the tailings dam.The simulation results showed that the higher the water level,the lower the stability of the dam.Observation points were arranged,it was found that the maximum displacement occurred in the surface soil which was distributed at the top and rear ends of the primary dam.Considering the interface effect,the stability coefficient of the dam at normal water level decrease from 1.733 to 1.230,and the stability coefficient of the dam at flood level decrease from 1.392 to 1.223,indicating that the introduction of the interface effect lead to a decrease in the stability of the dam. |
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